Referee Paul Tierney has reportedly admitted he made a mistake when he awarded Raheem Sterling's first goal of three as Manchester City beat Watford on Saturday.

Sterling's goal had initially been cancelled out by Tierney's assistant Adrian Holmes, but the official overruled the decision and gave the goal anyway.

Replays showed that Sterling was clearly in an offside position when the ball is played to him by team mate Sergio Aguero and, according to The Sun, Tierney has since admitted to making the mistake.

The incident has sparked debate about Tierney's performance and someone who was unimpressed with the decision was former referee Mark Halsey who criticised the official live on TalkSport on Sunday morning and accused him of trying to be "too clever".

He said: "As a referee, all day long, it that flag goes up for an offside offence I am blowing and giving the offside.

"I think Paul Tierney’s tried to be too clever. He’s guessed it wrongly.

"Sterling is always offside [in this incident].

"It doesn’t necessarily mean being in an offside position you are committing an offence, its when you become involved in active play.

"For me, that met the criteria yesterday and Raheem Sterling should have been flagged offside."

Halsey is not the only one to have spoken against the decision, with the Professional Game Match Officials Limited (PGMOL) issuing a statement on Sunday to say that Tierney's decision was incorrect.